The invention relates to recognizing faults in machines. More particularly, the invention relates to a system and method for recognizing potential faults and actualfaults in machines from machine data.
Faults in electrical, mechanical and electromechanical machines are often detected by sensors, which measure the machines' performance. For example, as material is transported through a machine it may be expected to cross the path of a sensor within a certain time expectation. Often, expectations like this are not achieved, particularly when a machine is starting to fail or has failed. Expert systems are often employed to simulate the judgment of a human operator (e.g. a repair technician who must diagnose specific machine faults). Characteristically, an expert system contains a knowledge base having accumulated experiences for applying the knowledge base to each particular machine fault. The knowledge base is usually represented by a fault tree, which is used to guide an operator to a specific fault, and thus a solution for repairing the machine. When there is a machine fault, the operator, using the expert system, accesses the fault tree and proceeds down the tree through question and answer sessions presented to the operator. This is typically a manual process where the operator is presented with a series of questions, and depending upon the operator's answers, the expert system presents other related question, which steps the operator down a specific path in the fault tree. Essentially, the expert system guides the operator down the fault tree, where he or she ultimately reaches a point in the tree where information regarding the specific fault of the machine is provided. Having this information, the operator can isolate the problem area of the machine and address the necessary repair.
A problem with the above expert system approach to diagnosing a fault within a machine is that most machines have numerous modules or subsystems, any of which could house the fault. If the operator is unsure of which module or subsystem has failed, the operator must start at the top of the fault tree and work his or her way down the tree until the fault is isolated. This procedure is very time consuming and increases the down time of the machine, as well as the chances of misdiagnosis. If the operator is savvy, then he or she may jump to a particular subsystem (or subtree) within the fault tree and bypass preliminary diagnosis procedures. This saves operator time, but only if the operator is correct in his or her preliminary diagnosis of the fault. If the operator is incorrect, then the expert system will take him or her down an incorrect path of the fault tree. Additionally, if the machine has different operators, then each operator is likely to respond differently to a fault, which would result in different fault response times. Moreover, since this process has significant operator involvement, it lends itself to operator error. Even if the operator cautiously steps through the fault tree, he or she could incorrectly assess the machine information or incorrectly answers a question presented by the expert system and indirectly proceed down an incorrect path of the fault tree. What is needed is a system and method that uses machine data to recognize potential or actual faults and guide a conventional expert system through a diagnosis process, thereby increasing the speed and accuracy of a diagnosis and repair of the machine, and minimizing time consuming human interaction and assorted error.